CNC.JS Model not on plane

Whats causing the model not to be exactly on the plane?

Do you want the starting point to be in the middle of the work piece? That has to be adjusted in the cam(set zero). Or are you thinking about the size of the work plane grid? I think that setting can be changed within cnc.js. I’m not sure if it matters though. If you jog to the corners of your workpiece, you’ll quicjly see if you are constrained or not.

Are you saying the path isn’t on Z=0? The path is where the very tip of the bit is going to travel. So if you are cutting 3mm down, that pattern will be at -3mm in Z. That is all determined by CAM.

If you need a check, ncviewer.com works well enough.